1. Field of the Invention
The invention relates to a printing apparatus having a plurality of paper feeding units, a printing method, and a printing system.
2. Related Background Art
Hitherto, a printing apparatus having a plurality of paper feeding units has been known. The printing apparatus generally has an automatic paper feeding mode and is constructed so that it can select a paper feeding unit for actually feeding papers for a printing process in accordance with a situation. For example, in case of printing print information received from a host computer, the paper feeding unit in which recording papers of the same size as a paper size that is decided by format information or the like have been enclosed is automatically selected. However, when the recording papers of the optimum size don't exist in any of the paper feeding units, the paper feeding unit in which the recording papers of the size that is nearer to the optimum size have been enclosed is selected or the paper feeding unit which has already been selected at the time of receipt of the print information is selected as it is.
The printing apparatus is also constructed in a manner such that even during a printing process by the paper feed of the selected paper feeding unit, recording papers can be ordinarily newly supplied to the other paper feeding units.
In the above printing apparatus, however, when the paper feeding unit is once selected and the printing process is started, since the paper feeding unit to feed the paper for the printing process has been fixed irrespective of the presence or absence of a change in status of the recording papers to be enclosed in the other paper feeding units, even if the recording papers of a more proper size are newly supplied to the other paper feeding unit, they cannot be soon used.
In the case where the recording papers of the size different from the recording paper size which has been preset as recording papers to be inherently enclosed in the other paper feeding unit are newly supplied to the relevant other paper feeding unit during the printing process and the operator is not aware of such a paper supply but forcedly selects such other paper feeding unit at the time of the next printing process or the like, there is a fear such that the printing process is performed by the recording paper of an improper size.
Further, when the output papers are removed from a paper ejecting unit by someone during the printing process and the operator is not aware of such a removal or the like, there is a fear such that all of the output papers cannot be certainly captured or it is necessary to again print.